1. Field
The present invention relates to a rechargeable battery in which an electrode terminal is made of different metals.
2. Description of the Related Art
A rechargeable battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter is incapable of being recharged. A low-capacity rechargeable battery is used in small portable electronic devices such as mobile phones, notebook computers, and camcorders, while a high-capacity rechargeable battery can be used as a power source for driving motors of a hybrid vehicle, an electric vehicle, and the like.
For example, a rechargeable battery typically includes: an electrode assembly for performing charging and discharging operations; a case in which the electrode assembly and an electrolyte solution are accommodated; a cap plate combined to an opening of the case; and electrode terminals provided in the cap plate to be connected to the electrode assembly (e.g., negative and positive electrode terminals).
The electrode assembly is formed by winding a negative electrode, a separator, and a positive electrode together in a jelly roll state. A current collector of the negative electrode is formed of a thin copper plate, while a current collector of the positive electrode is formed of a thin aluminum plate. Accordingly, the current collector of the negative electrode is connected to the negative terminal via a copper lead tab, and the positive electrode current collector is connected to the positive electrode terminal via an aluminum lead tab.
The negative and positive electrode terminals are made of aluminum to be connected to a bus bar. Accordingly, since the lead tab connected to the negative electrode is made of copper, the negative terminal includes a copper terminal and an aluminum terminal that are made of different metals.
In this case, the negative terminal is formed by joining the copper terminal connected to the lead tab and the aluminum terminal connected to the bus bar through friction welding. Such friction welding increases a manufacturing cost of the negative terminal and the rechargeable battery.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.